Riser Fracture Gate Casting Solutiona Figure shows the hot t

Solution

a) Figure shows the hot tearing which are hot cracks which appear in the form of fracture surface. They arise when the solidifying metal does not have the sufficient strength to resist tensile forces produced during solidification.

They are chiefly from an excessively high temperature casting metal, increased metal contraction, incorrect design of the gating system and non uniform cooling, which give rise to internal stresses.

This defect can be avoided by improving the design of the casting and by having the mould of low hot strength and large hot deformation.

b) Figure shows the the defect which is cut or wash which mainly occurs on the drag surface of the casting that extends along the surface, decreasing in heights as it extends from one side of the casting to other.

It usually occurs with bottom gating casting in which the molding sand has insufficient hot strength, and when too much metal is mde to flow through one gate into mould cavity.